Field of the Invention
The main object of the present invention is to provide an electric power supply, for example an electric supply for a rapid switching device with PIN or power diodes.
Electronic scanning antennas or aerials comprise one or several primary radiation sources and a network of phase shifters associated with elementary sources. Phase shifters comprising PIN diodes are often used. The phase shifting is obtained either by carrying out a shifting between paths having different lengths, or by causing to vary the reactances of the PIN diodes, according to whether they are in their passing state or in their blocked state.
With an electric scanning antenna, the electromagnetic energy beams are directed, by forming an equiphase plane perpendicular to the direction of the beam. The spacial coverage of the beam is limited by the time required to change the phase shiftings of each elementary source of the antenna. An increase in the speed of phase shifting of the various elementary sources of the antenna allows for the tracking of a greater number of targets.
The transition, called switching between the non-conductive state and the conductive state of the phase shifting PIN diodes is performed rapidly. On the contrary, the inverted switching, in the non conductive direction is not performed instantaneously. Due to this fact, with a voltage source at the terminals of the PIN diodes at the moment of switching, each PIN diode starts to behave as a short-circuit where the reverse current becomes high, and is then blocked. At this moment when the polarity of the voltage applied to the junction of each PIN diode is reversed, the current in the diode increases rapidly. This reverse current is due to the shifting of the minority carriers, previously stored during the direct conduction period at the level of the junction. The quantity of the stored charges is a function of the characteristics of the diode, of the life-span of the minority carriers and of the direct current prior to switching. The flow of these charges is ensured by blocking means that produce a reverse current achieved through elimination of the charge carriers. Thus, the switching rapidity is associated with the intensity of the current supplied by the blocking means.
According to the prior art, the blocking means that supply a reverse current once it is desired to establish the blocking of the diodes is constituted by a high voltage source having a large resistor. The high voltage supply is bulky and must supply a large current. Due to this fact, the feeding power is considerable and the thermal dissipation high. This results in temperature increases of the blocking device of the diodes.